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1
Chang, Siu Hua, e Siti Fatimah Abdul Halim. "Recovery of Precious Metals from Discarded Mobile Phones by Thiourea Leaching". Materials Science Forum 962 (luglio 2019): 112–16. http://dx.doi.org/10.4028/www.scientific.net/msf.962.112.
Testo completoAbstract (sommario):
The objective of this work was to recover gold and silver from the printed circuit board (PCB) of discarded mobile phones by thiourea leaching. Effects of thiourea concentration, leaching temperature, leaching time, and ferric ion (Fe3+) concentration on the recovery of gold and silver were investigated. The PCB was pretreated physically to reduce the thiourea consumption and enhance the leaching process. It was found that the percentage of gold leaching was higher than that of silver at different conditions studied. The highest percentages of gold (96%) and silver (90%) leachings were achieved with 20 g/L of thiourea and 8 vol% of Fe3+ at 4 h of leaching time and 25°C of leaching temperature.
2
B., Manoj, Kunjomana A. G. e Mansoor Ahmad. "Effect of Leaching High Ash Coal by Hydrofluoric Acid and EDTA on Removal of Mineral Matter and Sulphur". Mapana - Journal of Sciences 8, n. 2 (30 novembre 2009): 29–37. http://dx.doi.org/10.12723/mjs.15.4.
Testo completoAbstract (sommario):
Demineralization of coal was carried out using EDTA and HF. The residual coal from each treatment was characterized together with virgin coal using Scanning Electron Microscopy and energy dispersive X-ray analysis (EDAX). An elemental analyzer was adopted to analyze CHNS on virgin and residual coal sample. The current research compares the leaching efficiency of a mild leachant and a strong leachant. The final analysis showed that the coal under study was subbituminous coal and leaching could improve the amount of carbonaceous material. It was observed that with HF leaching aluminates silicates and calcites are removed completely where as only feaces of sulphur remained. With EOTA leaching only calcium was removed. The Carbon content is increased to 77.461 from 60.121.
3
Kosanlavit, Waraporn, e Napat Noinumsai. "Effects of Nanoscale Zero-Valent Iron on Soil-Leaching of Trinitrotoluene Contaminated Soil in Acid Rain Conditions". Key Engineering Materials 907 (21 gennaio 2022): 66–73. http://dx.doi.org/10.4028/www.scientific.net/kem.907.66.
Testo completoAbstract (sommario):
The study of effects of nanoscale zero-valent iron (nZVI) on soil-leaching of trinitrotoluene (TNT) contaminated soil in the acid rain conditions is aim to the determination of the effect of nZVI which used as treatment material on soil leaching of TNT contaminated soil in raining condition. Research methodology, soil leaching batch reactor was designed for TNT remediation in soil with nZVI. The reactor was divided into three compartments for the different series of the experiment. Three compartments of the experiments were used for 1) TNT-contaminated soil column (without leaching), 2) TNT-contaminated soil was leached with rainwater, and 3) TNT-contaminated soil was mixed with nZVI and leached with rainwater. The leachants in the experiment were distilled water (pH 6-6.5) and artificial rainwater (pH≈5). The results of this study found the highest TNT removal efficiency was obtained from in the leaching column with nZVI, followed by the leaching column without nanoparticles and non-leaching column at 100.00, 37.25, and 10.65 % respectively. The leachant (artificial rain) which was slightly acidic in pH could remove some of TNT. The leachant improved solubility and transformation of nitro group in TNT to amino group by H ions addition. The results of the current study can be used to predict the circumstances of leaching TNT on-site in the rainy season.
4
Park, Yujin, Yuik Eom, Kyoungkeun Yoo e Manis Kumar Jha. "Leaching of Copper from Waste-Printed Circuit Boards (PCBs) in Sulfate Medium Using Cupric Ion and Oxygen". Metals 11, n. 9 (30 agosto 2021): 1369. http://dx.doi.org/10.3390/met11091369.
Testo completoAbstract (sommario):
In the present paper, the leaching of copper from printed circuit boards (PCBs) using sulfuric acid with Cu2+ and O2 is proposed. The effects of various process parameters such as agitation speed, temperature, the type and the flow rate of gas, initial Cu2+ concentration, and pulp density were investigated to examine the dissolution behavior of Cu from PCBs in 1 mol/L sulfuric acid. The kinetic studies were performed using the obtained leaching data. The leaching rate of Cu from PCBs was found to be higher on addition of Cu2+ and O2 to the leachant in comparison with the addition of O2 or both Cu2+ and N2 in the leachant. The leaching efficiency of Cu was found to be increased with increasing agitation speed, temperature, O2 flow rate, and initial Cu2+ concentration and decreasing pulp density. The 96% of Cu leaching efficiency was obtained under the following conditions: sulfuric acid concentration, 1 mol/L; temperature, 90 °C; agitation speed, 600 rpm; pulp density, 1%; initial Cu2+ concentration, 10,000 mg/L; and O2 flow rate, 1000 cc/min. The leaching data and analyses indicate that the Cu leaching from PCBs followed the reaction-controlled model satisfactorily and determined that the activation energy was found to be 23.8 kJ/mol. Therefore, these results indicate that the sulfuric acid solution with Cu2+ and O2 as a mild leach medium without strong oxidants such as HNO3, H2O2, and Fe3+ is valid for Cu leaching from PCBs.
5
Sahu, Sibananda, Subhankar Pati e Niharbala Devi. "A Detailed Kinetic Analysis of the Environmentally Friendly Leaching of Spent Lithium-Ion Batteries Using Monocarboxylic Acid". Metals 13, n. 5 (13 maggio 2023): 947. http://dx.doi.org/10.3390/met13050947.
Testo completoAbstract (sommario):
It is essential to develop a leaching procedure that uses minimal acid consumption, is economical, recovers large amounts of metal, and has a minimal negative impact on the environment. In this paper, a viable hydrometallurgical method using acetic acid as a leachant is suggested for recovering critical metals from waste LCO-type batteries. Several leaching parameters were examined in order to optimize the leaching conditions. With 1.2 mol/L acetic acid, 7% H2O2, 90 °C, an S/L ratio of 10 g/L, and a 60 min leaching period, the maximum leaching efficiencies of Li (99.6%) and Co (95.6%) were attained. By investigating the different kinetic models, it was feasible to figure out the reaction’s pace, as well as the mechanism involved in the leaching process. It was found, through the comprehensive kinetic studies of the leaching process, that the surface chemical reaction controls the leaching mechanism for waste LCO-type batteries. The economic viability of the current leaching procedure in comparison to those of earlier approaches is also discussed.
6
Zha, Fusheng, Congmin Liu, Bo Kang, Long Xu, Chengbin Yang, Chengfu Chu, Chuang Yu, Wei Zhang, Jiwen Zhang e Zhenghong Liu. "Effect of Carbonation on the Leachability of Solidified/Stabilized Lead-Contaminated Expansive Soil". Advances in Civil Engineering 2021 (11 febbraio 2021): 1–13. http://dx.doi.org/10.1155/2021/8880818.
Testo completoAbstract (sommario):
Lime, fly ash, and alkaline residue are used widely as effective binders to solidify/stabilize heavy metal-contaminated expansive soil. Carbonation, however, may influence the effectiveness of solidification/stabilization (S/S) by decomposing hydration products and decreasing pH, which would seriously damage the long-term durability of stabilized soils. This study focused on the variation of leaching characteristics of solidified/stabilized lead-contaminated expansive soils before and after accelerated carbonation under the leachant of pH 3 and 5 by the semidynamic leaching test. After semidynamic leaching, leaching indexes such as the effective diffusion coefficient (De), leachability index (Lx), and slope (rc) were used to reveal the ion leaching mechanism. The results indicated that the amount of Pb2+ and Ca2+ leached out under different pH conditions increased after carbonation, which confirmed that carbonate on solidified/stabilized lead (Pb) had a negative impact. Additionally, the De values of Pb2+ and Ca2+ varied in the range of 1.16E − 10 cm2/s to 1.71E − 07 cm2/s, which demonstrated that ion migration was low. The contaminated soil solidified by lime and AR could be used in “controlled utilization” as Lx was higher than 9, and the leaching process was controlled by a dissolution reaction according to the analysis of rc. Moreover, the strong acidic leachant (pH = 3) resulted in more ions leaching out and lower pH in leachate compared with a mildly acidic leachant. Finally, with literature and experimental results, we found that the main reason for the increase of lead ion filtration of the carbonation reduced the pH value of the matrix and made the hydration products denatured and decomposed.
7
Mohd Rozali, Mohd Fasyraf Hafizi, Nurulfazielah Nasir, Suhaina Ismail e Norazharuddin Shah Abdullah. "Preliminary Studies on Acid Leaching of Finely-Ground Malaysian Low Grade Manganese Ore (LGMO)". Materials Science Forum 840 (gennaio 2016): 364–68. http://dx.doi.org/10.4028/www.scientific.net/msf.840.364.
Testo completoAbstract (sommario):
Ore samples, believed to be low grade manganese ore were characterized using XRD, XRF and SEM, before being ground further into very fine particle sizes going through a preliminary leaching process. Sulfuric acid was chosen as the leachant, and leaching was done without any presence of reducing agents.
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Munir, Badrul, Sulaksana Permana, Anggita Amilia, Ahmad Maksum e Johny W. Soedarsono. "Initial Study for Cerium and Lanthanum Extraction from Bangka Tin Slag through NaOH and HClO4 Leaching". MATEC Web of Conferences 269 (2019): 07003. http://dx.doi.org/10.1051/matecconf/201926907003.
Testo completoAbstract (sommario):
The global demand for rare earth elements have increased dramatically for the last decade as more and more devices use rare earth elements as key for their advanced properties. The paper explores the possibilty to recover cerium (Ce) and lanthanum (La) in Bangka tin slag (BTS) involving roasting at 900°C, water-quenching, and two leachings, 8M NaOH leaching and HClO4 leaching at concentrations of 0.1M, 0.4M, and 0.8M. HClO4 leaching causes Ce and La contents to decrease to 0.47% for 0.1M, 0.51% for 0.4M, and 0.59% for 0.8M. On the other hand, 8M NaOH optimizes cerium and lanthanum contents up to 4.35% and 1.45%, respectively.
9
Keel, Kevin R., Charles H. Gilliam, Glenn R. Wehtje, Tim L. Grey, Gary J. Keever e Donald J. Eakes. "Herbicide Adsorption and Release Properties of Five Oxadiazon-Coated Fertilizers". Journal of Environmental Horticulture 16, n. 4 (1 dicembre 1998): 230–34. http://dx.doi.org/10.24266/0738-2898-16.4.230.
Testo completoAbstract (sommario):
Abstract Laboratory experiments were conducted to determine the release of oxadiazon coated on control-release fertilizers. Five fertilizers and glass beads (nonabsorbent control) were coated with 14C-oxadiazon + formulated oxadiazon at a herbicide-to-fertilizer concentration of 0.3 mg ai/g. Coated fertilizers were subjected to 14 consecutive daily water leaching events. For the control-release fertilizers, Nutricote, Meister and Osmocote, 70%–80% of the coated oxadiazon was released in the first 3 leaching events; each leaching event after the 7th leaching event contained less than 1% of total applied oxadiazon. In contrast, 56% of the total applied oxadiazon was leached from Polyon 24N–1.7P–10K (24–4–12) in the first 3 leachings and similar percentages of oxadiazon were leached over each of the last 11 leaching events. Coating the five fertilizers with isoxaben produced similar results. A second experiment evaluated the effects of the addition of Prime Oil, Complex (sticker), Plex (sticker), and Intac (sticker) on release rates of oxadiazon-coated Osmocote 17N–3.1P–10K (17–7–12). Oxadiazon-coated Osmocote alone and oxadiazon-coated Polyon alone were also evaluated. Eighty-five percent of the total applied oxadiazon was leached from oxadiazon-coated Osmocote alone during the first leaching event and less than 1% was recovered with each consecutive leaching after the third leaching. Oxadiazon-coated Osmocote treated with Plex responded similarly to oxadiazon-coated Osmocote. Oxadiazon-coated Osmocote treated with Complex, Intac, or Prime Oil and oxadiazon-coated Polyon lost 21%, 20%, 16%, and 24%, respectively, of the applied herbicide after the first leaching event. Thereafter, nearly equal amounts of oxadiazon (5%) were leached from Complex, Prime Oil, Intac and Polyon alone from the 6th through the 11th leaching events.
10
Ma, Guo Jun, Hui Tang e Yi Biao Jin. "Mineral Sequestration of CO2 Using Basic Oxygen Furnace (BOF) Steelmaking Slag". Advanced Materials Research 194-196 (febbraio 2011): 2140–44. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.2140.
Testo completoAbstract (sommario):
A promising option for long-term storage of CO2 is to fix CO2 by industrial solid wastes, such as basic oxygen furnace (BOF) steelmaking slag. It is advantage to use BOF steelmaking slag to fix CO2, such as large volume of BOF steelmaking slag, low price of raw materials, close to the CO2 emission sources, and no secondary pollution. It is of great significance to the CO2 emissions reduction and solid waste disposal in the ironmaking and steelmaking plant. In this paper, the leaching process, impurities removing and carbonation of steelmaking plant waste slag were studied at ambient pressure. The results show that Ca2+ leaching mainly occurs at the beginning 60min in the leaching process. The Ca2+ leaching ratio can reach about 45% with the leachant of 2mol/L HAc, leaching temperature of 30°C and solid-liquid ratio of 1:20. Moreover, it can effectively remove Mg2+, Al3+ and Fe3+ by adding small amounts of NaOH and triethanolamine in the leaching solution, and thereafter, high purity CaCO3 products can be obtained through the carbonation process.
11
Yang, Jinlin, Xingnan Huo, Zongyu Li e Shaojian Ma. "Study on Hydrometallurgical Treatment of Oxide Ores Bearing Zinc". Minerals 12, n. 10 (7 ottobre 2022): 1264. http://dx.doi.org/10.3390/min12101264.
Testo completoAbstract (sommario):
As the depletion of zinc sulfide ores becomes more severe, investigations into the recovery of zinc from zinc oxide ores have aroused more interest. In this regard, acid-based hydrometallurgical treatment strategies have had great effectiveness. However, they are inadequate for low-grade zinc oxide ores. In this study, we examined the alkaline treatment of gossan for the recovery of oxide ores that bear zinc, such as siderite and limonite. Additionally, of particular note, the effects of a leaching agent, its concentration and time, temperature, liquid-to-solid ratio, as well as the agitation rate on the leaching of zinc from gossan were studied to evaluate the effects of these parameters on the kinetics of zinc dissolution. The results showed that the leaching of zinc is controlled by a single rate-controlling step with an activation energy of 4.458 kJ/mol before 120 min and 5.536 kJ/mol after 120 min, with zinc leaching efficiency less than 50% in all leachings.
12
Cheng, Jun Hua, Jian Zhang e Di Jiang Wen. "Comparison of Leaching Characteristics of Lead in Waste CRTs". Advanced Materials Research 177 (dicembre 2010): 470–74. http://dx.doi.org/10.4028/www.scientific.net/amr.177.470.
Testo completoAbstract (sommario):
This study investigates four extraction methods (water extraction, toxicity characteristics leaching procedure (TCLP), modified TCLP with pH control and sequential chemical extraction (SCE)), each representing different liquid-to-solid (L/S) ratios, pH controls, and types of leachant and their effects on the leaching concentration of Pb in cathode ray tubes (CRTs).The results indicated that for extraction with distilled water,the lead leaching concentration (mg/L) decreased with L/S ratio in the range of 2-100. The results also showed that the leaching concentration was strongly pH-dependent in the TCLP and modified TCLP tests. In modified TCLP tests,in the case of pHs lower than 6.3,the leaching concentrations of Pb decreased with an increase in pH. Due to the nature of amphoteric elements, in the case of pHs higher than 7, the Pb leaching concentration increased with increasing pH. In SCE tests, the Pb speciation approached the extractable carbonate bound fraction. Both amounts of Pb leached from the SCE and modified TCLP tests were much higher than those for the regular TCLP and water extraction tests. The initial particle size of samples have great effect on the leachability of Pb from waste CRTs.
13
Leelarungroj, Kittitat, Suched Likitlersuang, Thanakorn Chompoorat e Dao Janjaroen. "Leaching mechanisms of heavy metals from fly ash stabilised soils". Waste Management & Research: The Journal for a Sustainable Circular Economy 36, n. 7 (12 giugno 2018): 616–23. http://dx.doi.org/10.1177/0734242x18775494.
Testo completoAbstract (sommario):
Fly ash is an industrial waste material that is repurposed as a soil stabiliser worldwide. In Thailand, many ground improvement projects utilise mixtures of cement and fly ash to stabilise weak soils. In this study, leaching mechanisms of arsenic, chromium, lead, and zinc from cement and fly ash stabilised soils were investigated in the laboratory. Leaching tests were performed, with different leachants and pH conditions, on cement and fly ash stabilised soils used for soil improvement in road embankment construction projects in Northern Thailand. The results suggested that chemical compounds (CaO and MgO) on fly ash surfaces can control the pH of the fly ash and soil leachant. The dissolution of chromium and zinc was found to be amphoteric and controlled by oxide minerals at a high or low pH. Arsenic leaching was found to be oxyanionic where AsO43- prevented the adsorption of arsenic onto the negatively charged fly ash surface. Different types of leachant also leached out in different amounts of heavy metals.
14
Zhang, Yanhao, Haohan Zhang, Zhibin Zhang, Chengying Liu, Cuizhen Sun, Wen Zhang e Taha Marhaba. "pH Effect on Heavy Metal Release from a Polluted Sediment". Journal of Chemistry 2018 (23 agosto 2018): 1–7. http://dx.doi.org/10.1155/2018/7597640.
Testo completoAbstract (sommario):
The performance of Cd, Ni, and Cu release from river sediment at different pH was investigated by a leaching test using deionised water and river water as leachants. Visual MINTEQ geochemical software was used to model the experimental results to predict heavy metal release from sediments. The distribution and speciation of heavy metals in the sediments after leaching test were analyzed by Tessier sequential extraction. Leaching test results showed that the release amounts of Cd, Ni, and Cu are in the range of 10.2–27.3 mg·kg−1, 80.5–140.1 mg·kg−1, and 6.1–30.8 mg·kg−1, respectively, with deionised water as leachant at different pH. As far as the river water was used as the leaching solution in the test, the results show similar metal leaching contents and tendencies to that of the deionised water as leaching solution. The results of Tessier sequential extraction indicate that Cd of residual fraction easily forms obvious precipitate under the acidic condition, especially in the range of pH 0–4 with the residual of Cd over 50% of the total Cd in the sediment. The exchangeable content of Ni decreases with the increase of pH under the range of 0–5. The Fe-Mn oxide fraction of Cu in the sediments changes significantly from pH 0 to pH 9. Based on the effect of pH on the leaching of Cd, Ni, and Cu from the polluted sediment in the tests, more accurate information could be obtained to assess the risk related to metal release from sediments once it is exposed to the changed acid/alkali water conditions.
15
Sakai, Shin-ichi, Satoshi Mizutani e Hiroshi Takatsuki. "Leaching Procedure. Leaching Tests for Waste Materials." Waste Management Research 7, n. 5 (1996): 383–93. http://dx.doi.org/10.3985/wmr.7.383.
Testo completo
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Yang, Jing, Wenqi Guo, Chengsen Zhao, Biqing Zhou, Wenhao Yang, Shihe Xing e Fenghua Ding. "Increased Soil Soluble Nitrogen Stocks and Decreased Nitrogen Leaching Loss in Rice Paddy Soil by Replacing Nitrogen Fertilizer with Chinese Milk Vetch". Agronomy 14, n. 4 (29 marzo 2024): 715. http://dx.doi.org/10.3390/agronomy14040715.
Testo completoAbstract (sommario):
Reducing soil nitrogen leaching losses and improving nitrogen-use efficiency with effective fertilization management strategies are extremely important for sustainable agricultural development. A 2-year field study was executed with the same nitrogen input in a subtropical rice production system in Southeast China, using chemical fertilizers as a control (CK), to study the influences of different application amounts of Chinese milk vetch (CMV), i.e., 15,000 kg hm−2 (CL), 30,000 kg hm−2 (CM), and 45,000 kg hm−2 (CH), on soil soluble nitrogen stock and leaching risks in a clay paddy field. The results showed that the soil stocks of soluble inorganic nitrogen (SIN) and soluble organic nitrogen (SON) in a 0–60 cm soil profile under different application amounts of CMV significantly increased by 12.43–36.03% and 19.43–71.75% compared with CK, respectively, which was more favorable to soil SON accumulation. In the 2-year experiment, the total dissolved nitrogen leaching loss was 23.51–61.88 kg hm−2 under different application rates of CMV, of which 50.08–62.69% was leached by dissolved inorganic nitrogen (DIN), and 37.31–49.92% was leached by dissolved organic nitrogen (DON). CMV application improved soil properties (pH, SOM, and urease/protease), increased SIN and SON stocks, and decreased surface water DIN and DON concentrations, thereby reducing DIN and DON leaching. The leachings of DIN and DON in different application rates of CMV were reduced by 11.37–66.23% and 13.39–52.07% compared with the CK treatment, respectively. Conclusively, nitrogen leaching loss in paddy fields was severe, and the DIN and DON leaching loss in CMV treatments were lower than those in the control under the same nitrogen input. Thus, replacing nitrogen fertilizer with CMV under the same nitrogen input could reduce the risk of nitrogen nonpoint pollution in clay paddy fields.
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Wajima, Takaaki. "Effects of Step-Wise Acid Leaching with HCl on Synthesis of Zeolitic Materials from Paper Sludge Ash". Minerals 10, n. 5 (29 aprile 2020): 402. http://dx.doi.org/10.3390/min10050402.
Testo completoAbstract (sommario):
Incinerated ash with a relatively high Ca content, paper sludge ash, was converted to zeolitic materials with high cation-exchange capacities (CECs) by aging at 80 °C in NaOH solution via step-wise acid leaching with HCl to reduce the ash Ca content. The extraction of Ca, Mg, Si, and Al from the ash into the acid solutions during leaching and the products obtained from the leached ash by reaction with an alkali were examined. The contents of Ca and Mg in the ash were more easily extracted from the ash than those of Si and Al in the initial leaching. The leachant pH decreased with increasing numbers of leaching steps, and the amounts of Si, Al, and Ca extracted from the ash increased as a result of the dissolution of gehlenite (Ca2Al2SiO7), one of the main minerals in the ash. Zeolites A and P were synthesized from the leached ashes, and hydroxysodalite was synthesized from the raw ash. With increasing numbers of leaching steps of the ash, the obtained product contained lower released Ca, whereas the product contained higher released Na and has higher CEC, depending on the zeolite phases in the product. The product with the highest CEC was synthesized from third-leached ash, and its CEC was 1.5 mmol/g, which is about four times higher than that of the raw ash (0.4 mmol/g).
18
Dhawan, Heena, e Durlubh Kumar Sharma. "Advances in the chemical leaching (inorgano-leaching), bio-leaching and desulphurisation of coals". International Journal of Coal Science & Technology 6, n. 2 (24 maggio 2019): 169–83. http://dx.doi.org/10.1007/s40789-019-0253-6.
Testo completo
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Richter, Constanze, Harald Kalka e Horst Märten. "Potential Bioleaching Effects in In Situ Recovery Applications". Solid State Phenomena 262 (agosto 2017): 456–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.456.
Testo completoAbstract (sommario):
The potential role of microorganisms in the in-situ recovery (ISR) of technology metals, in particular from reduced ores, is not well understood, but attracts increasing interest worldwide. Based on the feasibility criteria for ISR applications in general, effects of biota on kinetic rates of leaching are systematized. The indirect catalysis of leaching by microbial (re-)oxidation of Fe2+ to Fe3+ as directly acting e- acceptor is a well verified mechanism, however, for practical applications this requires the availability of an oxidant in the leachant. The ex-situ bio-oxidation of Fe in an aerated bioreactor is considered as an alternative. Reactive transport simulations of ISR from sulfidic Cu ores based on kinetic rates as function of pH and oxidation potential (concentration of e- acceptors) in comparison with thermodynamically driven metal dissolution (constrained by oxidation potential) demonstrate the key parameters for (bio-)leaching productivity.
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Dandautiya, Rahul, Ajit Pratap Singh e Sanghamitra Kundu. "Impact assessment of fly ash on ground water quality: An experimental study using batch leaching tests". Waste Management & Research: The Journal for a Sustainable Circular Economy 36, n. 7 (31 maggio 2018): 624–34. http://dx.doi.org/10.1177/0734242x18775484.
Testo completoAbstract (sommario):
The fly ash, generated at the coal-based thermal power plant, is always a cause of concern to environmentalists owing to its adverse impact on air, water and land. There exists a high environmental risk when it is disposed to the environment. Thus, two different type of fly ash samples (FA-1 and FA-2) have been considered in this study to examine the leaching potential of the elements magnesium, aluminium, silicon, calcium, titanium, vanadium, chromium, manganese, iron, nickel, cobalt, copper, zinc, arsenic, selenium, strontium, cadmium, barium and lead for different types of leachant. Toxicity characteristics leaching procedure and ASTM tests have been performed in the laboratory to simulate different natural leaching scenarios. Characterisation of samples have been done through X-ray diffraction and field emission gun scanning electron microscope. The effect of different liquid to solid ratios (i.e. 5, 10, 20 and 50) on the mobilisation of elements has been analysed. The results indicated that the maximum leaching of all elements occurred at a liquid to solid ratio of 5 except for arsenic, barium and silicon. The groundwater analysis has also been done to understand the actual effects of leachate. The elements presenting the highest leachability in the two fly ash samples under all tested conditions were magnesium, aluminium, silicon and calcium. It has been observed that calcium exhibits greater leaching effects than all other constituents. The study presented here has been found very useful for assessing contamination levels in groundwater owing to leaching effects of fly ash under different scenarios, which can be helpful to prevent spreading of the contaminants by efficient management of fly ash.
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Delmas, Francisco, Lucinda Gonçalves, Isabel M. Martins e Manuela Oliveira. "Magnesium Removal from TiC-TiB2 SHS-Powders by Controlled Hot Acid Leaching". Materials Science Forum 514-516 (maggio 2006): 594–98. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.594.
Testo completoAbstract (sommario):
TiC and TiC–TiB2 powder mixtures obtained directly from titanium (TiO2) and boron (B2O3 or B4C) raw-materials by reduction with magnesium by self propagating high temperature synthesis (SHS) contain, as impurity, large quantities of MgO under its periclase form, together in some cases with unreacted magnesium. Several leaching agents, namely hydrochloric acid, sulphuric acid, acetic acid and EDTA were tested aiming at removal of magnesium from these powders as required characteristic for further work. Several parameters as leachant concentration, pH, reaction time and temperature were evaluated. Alternative leaching methodologies were compared in order to achieve magnesium removal yields over 98% and minimising at the same time the expected high matrix losses due to TiC and/or TiB2 co-solubilisation. As main conclusion it was established that strong hydrochloric acid (6M) is the most efficient medium to remove magnesium from these particular TiC-TiB2 SHS mixtures. The leaching methodology used (controlled hot acid leaching under close conditions) allowed to minimise TiC and TiB2 solubilisation losses. Sulphuric acid is not an effective leaching medium and contaminates the resulting powder mixture with unfriendly sulphur. Using acetic acid, magnesium removal yield is low and titanium losses are considerable. On the other hand, low aggressive EDTA complexant leaves TiC-TiB2 matrix unalterable but residual MgO remains over 6%. The proposed process seems to have potential for application in the general field of semi-micro materials purification.
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Guerra, R. N. G., Carlos A. Nogueira e Fernanda Margarido. "Leaching Studies of Spent Zinc-Manganese Alkaline Batteries with Sulphuric Acid". Materials Science Forum 587-588 (giugno 2008): 763–67. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.763.
Testo completoAbstract (sommario):
The hydrometallurgical processing of metal bearing residues is one of the established routes envisaging metals recovery. In these processes, the leaching operation plays a central role as allows the solubilization of metals for further separation and recovery as pure products. This route can be applied to spent domestic batteries recycling, which studies on sulphuric acid leaching of spent alkaline batteries are reported in this paper. Material samples used in the trials were prepared concerning the real proportion of the most common sizes and shapes of batteries found in the usual stream of this type of wastes. The research involved the evaluation of some factors which affect leaching yields namely temperature, reaction time and stirring speed, through a two-level factorial design methodology and analysis of variance. In this study, other factors related with leachant concentration and stoichiometry were maintained constant. Zinc leaching yields were generally high and even near 100% when the high levels of the variables were used, meaning that zinc oxides present in the electrodes are very reactive to acid leachant. The variables had all positive effects being temperature the most significant factor (confidence level 99%) while the other factors were less significant (98.8% for time and 95% for stirring speed). Concerning manganese, leaching yields obtained were more dependent from the factors, being also positive and varying from 11% (for low levels of factors combination) to 89% (for high levels of factors combination). Temperature and time were highly significant (confidence levels above 99.9%) while stirring speed was less significant (97%). Contamination of leach liquors with iron was also evaluated since it is an impurity which requires special attention during the process development. For the higher levels of the factors (t = 1 h, T=80°C and ω=400 rpm) the final solution contained 10 g/L Zn, 15 g/L Mn and 3.2 g/L Fe. The removal of the iron from the solution is a necessary step prior to the separation and recovery of zinc and manganese.
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Devasia, Preston, e K. A. Natarajan. "Bacterial leaching". Resonance 9, n. 8 (agosto 2004): 27–34. http://dx.doi.org/10.1007/bf02837575.
Testo completo
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Perdana, Indra, Muhammad Irfan Rahman, Doni Riski Aprilianto, Himawan Tri Bayu Murti Petrus e Divita Hayyu Kinanti. "Kinetics and Thermodynamics Study of Ammonia Leaching on Spent LMR-NMC Battery Cathodes". Indonesian Journal of Chemistry 24, n. 3 (1 giugno 2024): 876. http://dx.doi.org/10.22146/ijc.93312.
Testo completoAbstract (sommario):
The recycling of spent lithium NMC-type batteries, widely used in electric vehicles, presents a challenge due to manganese content, which complicates metal separation and purification. This study explored a selective leaching process using ammonia to recover metals from high-manganese-content LMR-NMC cathodes. By adjusting the (NH4)2SO4 reagent concentration to 1–2 M and maintaining the temperature between 50–80 °C, the recovery rates of lithium, nickel and cobalt metals were enhanced, leaving manganese primarily as residue in the form of Mn(OH)₂ and (NH4)2Mn(SO4)2. A kinetics model, integrating an equilibrium-shrinking core model with a modified temperature-dependent Arrhenius approach, accurately simulates the metal recovery. The activation energies of the forward leaching reactions of Li, Ni, and Co were respectively (1.4331±0.0036)×105, (1.5494±0.0034)×105, and (1.5743±0.0040)×105 J/mol, while those for the backward reactions were (5.3307±0.0041)×105, (2.4753±0.0093)×105, and (1.6289±0.0092)×105 J/mol, respectively. The leaching mechanism was found to be exothermic, which allows maximum recovery at low temperatures. The findings highlight ammonia’s effectiveness as a selective leachant, significantly reducing manganese in the leaching solution, and streamlining nickel and cobalt separation, thus enhancing the recycling process’s efficiency and sustainability.
25
Lu, Rong Rong, Yi He Zhang, Feng Shan Zhou e Xin Ke Wang. "Research of Leaching Alumina and Iron Oxide from Bayer Red Mud". Applied Mechanics and Materials 151 (gennaio 2012): 355–59. http://dx.doi.org/10.4028/www.scientific.net/amm.151.355.
Testo completoAbstract (sommario):
Adopting Bayer red mud as raw material, researching five acid leaching of alumina and iron oxide methods, hydrochloric acid leaching, sulfuric acid leaching, mixed acid leaching and two methods of classification acid leaching, affecting on leaching ratio of Al and Fe in red mud. All the five acid leaching experiments have a good effect on the leaching ratios of alumina and iron oxide. The highest leaching ratios of alumina and iron oxide are 90.1% and 99.0% when the volume of hydrochloric acid and sulfuric acid are 25mL in the mixed acid leaching. Finally, obtain better condition of preparing flocculants solution for water treatment by leaching Fe and Al in red mud.
26
Yang, Jin Lin, Shao Jian Ma, Wei Mo, Jin Peng Feng, Xiu Juan Su e Gui Fang Wang. "Study on Recovering Zinc from Gossan". Advanced Materials Research 454 (gennaio 2012): 329–32. http://dx.doi.org/10.4028/www.scientific.net/amr.454.329.
Testo completoAbstract (sommario):
In this paper, the conventional physical separation method such as flotation, gravity separation, magnetic separation, alkaline leaching and sulfuric acid leaching were studied. The effects of grinding fineness, amount of agent, magnetic intensity, roasting temperature, roasting time, the leaching agent and leaching time on the leaching of zinc were investigated, respectively. The results show that the leaching rate of zinc is below 50% in the conventional alkaline leaching, and the leaching rate of zinc is below 85% and the leaching rate of iron is above 35% in sulfuric acid leaching. Compared with XRD pattern of the raw ore, the different diffraction peaks of smithsonite is off in alkaline leaching products. In sulfuric acid leaching, the different diffraction peaks of smithsonite are off in the leaching products when sulfuric acid concentration is less than 60 g/L. After 60 g/L, the different diffraction peaks of smithsonite and siderite are off in the leaching products.
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Young, John R., E. Jay Holcomb e Charles W. Heuser. "Greenhouse Growth of Marigolds in Three Leached Sources of Spent Mushroom Compost over a 3-Year Period". HortTechnology 12, n. 4 (gennaio 2002): 701–5. http://dx.doi.org/10.21273/horttech.12.4.701.
Testo completoAbstract (sommario):
Though high electrical conductivity (EC) levels are commonly held to be the primary limiting factor for using spent mushroom compost (SMC) as a growing substrate, EC can be reduced by leaching. This allowed SMC to be successfully used for growing plants. Leaching reduced EC of the substrate solution from as high of 30 dS·m-1 (mmhos·cm-1) to 2 to 3 dS·m-1, a level acceptable for growing plants. The initial EC and container capacity determined the number of leachings and total volume of water required to lower EC of SMC substrates to acceptable levels. As the concentration of SMC was increased, a higher number of leachings or larger volume of water were required to adequately reduce EC levels. In trials spanning 2.5 years, SMC was effectively used as a substrate in the production of marigold (Tagetes patula) `Yellow Girl'. Benefits to plant growth from SMC incorporation included a slow release of nutrients as the SMC decomposed and a good air-filled pore space/water-holding capacity when amended with a commercial nursery mix. From these trials, it is recommended that SMC be incorporated at rates of 25% to 50%. It is not recommended that SMC be used in concentrations over 50% because the EC may be too difficult to manage and the high levels of air-filled pore space of SMC. Though season may affect the initial EC level of SMC, such variation is minimized by leaching while differences in plant response are more likely to be attributed to environmental conditions. No differences in plant growth were observed among SMC sources.
28
Oliveira, Paula C., M. C. Rosa, Lucinda Gonçalves, Maria A. Trancoso e Carlos A. Nogueira. "Acid Leaching of Leather Tanning Sludges: Metals Behaviour". Materials Science Forum 587-588 (giugno 2008): 758–62. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.758.
Testo completoAbstract (sommario):
Sludges generated in leather tanning processing are very complex wastes with potential deleterious effect on the environment and its management constitutes a high cost for the companies. In this work, sludges from a Portuguese tanning company were characterized and leached with acid solutions in order to evaluate the metals removal yields. The sludges contain, as main metals, 15% Ca, 5% Fe and 2.2 % Cr, in a dry basis. Other minor elements namely Al, Ti, Zn, Pb and Cu were also detected. The leaching experiments were carried out with two types of acids – hydrochloric and sulfuric – and the effects of the reaction time, temperature and leachant concentration were evaluated. The reaction conditions strongly affected the chromium leaching yields, being temperature and acid concentration highly significant (confidence level above 99.9%). About 90% of Cr was leached using the higher levels of the factors (4h, 80°C and 2M H+, with both acids). Concerning the other major metals, iron leaching was very efficient (yields usually above 90%) whatever the conditions tested while calcium behaviour was quite different, depending on the type of acid used for the same H+ concentration: H2SO4 leaching efficiency was generally lower than HCl, probably due to the formation of less soluble calcium sulfate. The maximum calcium removal achieved was near 75%. The leaching process developed can be useful not only as a decontamination step of the tanning sludges, but also as a process for metals recovery to be potentially applied in an integrated recycling system, where several metal wastes from different sources could be processed.
29
Zhang, Zhenyue, Jing Yang, Wenda Guo, Ling Jiang, Wendou Chen, Defeng Liu, Hanjun Wu e Ruan Chi. "Analysis and Prediction of the Leaching Process of Ionic Rare Earth: A Data Mining Study with Scarce Data". Minerals 14, n. 6 (6 giugno 2024): 596. http://dx.doi.org/10.3390/min14060596.
Testo completoAbstract (sommario):
To unveil the impact of each condition variable on the leaching efficiency index during the heap leaching process of rare earth ore and establish a prediction model for leaching conditions and efficiency, common parameters in the heap leaching process of rare earth ore were selected. In addition, the pilot-scale test data were collected over 50 days. Based on the collected data, the Ordinary Least Squares (OLS) linear regression method was used for fitting analysis to determine each variable’s influence on the change in leaching efficiency. The results indicated a linear relationship between the flow rate of the leaching solution and leaching efficiency. In contrast, no obvious linear relationship was observed between other condition variables and leaching efficiency. Spearman’s rank correlation coefficient was calculated to analyze the nonlinear correlation between the abovementioned variables and the leaching efficiency index. The correlation coefficients were found to be −0.78, 0.88, −0.93, −0.53, 0.71, and −0.93 for ammonium content in the leaching agent, pH of the leaching agent, rare earth content, ammonium content in the leaching solution, pH of the leaching solution, and the flow rate of the leaching solution, respectively. This suggests that the flow rate of the leaching solution, rare earth content, and pH of the leaching agent significantly influence leaching efficiency, thus affecting the rare earth leaching efficiency index. Based on the correlation analysis results of leaching conditions and efficiency, a dataset with limited data trained by the common Ordinary Least Squares model, linear regression model, random forest model, and support vector machine regression model was selected to develop a prediction model for the leaching process data. The results indicated that the random forest model had the lowest mean square error of 7.47 among the four models and the coefficient of determination closest to 1 (0.99). This model can effectively analyze and predict condition variables’ data and leaching efficiency index in the heap leaching process of rare earth ore, with a prediction accuracy exceeding 90%, thus providing intelligent guidance for the heap leaching process of rare earth ores.
30
Xu, Zhigao, Gang Li, Huifang Yang, Aoyang Sha, Zhengyan He, Yuchen Tang, Ming Wu e Jun Qu. "Development Review on Leaching Technology and Leaching Agents of Weathered Crust Elution-Deposited Rare Earth Ores". Minerals 13, n. 9 (17 settembre 2023): 1223. http://dx.doi.org/10.3390/min13091223.
Testo completoAbstract (sommario):
Weathered crust elution-deposited rare earth ores are key strategic resources and the main source of medium and heavy rare earths. This paper summarizes the development of leaching technology of rare earth ores, compares the advantages and disadvantages of the three generations of leaching technology, and introduces the improved heap leaching technology and the new technology of the leaching–extraction integration and enhanced leaching, focusing on the leaching of weathered crust elution-deposited rare earth ores. In this paper, the development of the leaching agents is expounded, and the research status and the development trend of the composite ammonium salt leaching agent, impurity inhibition leaching agent, swelling inhibition leaching agent, and seepage-promotion leaching agent are also introduced. And this paper summarizes the leaching mechanism and the development direction of leaching agents. Moreover, the future key research direction of weathered crust elution-deposited rare earth ores is proposed, which is green, efficient, safe development and utilization.
31
Yang, Huifang, Aoyang Sha, Zhengyan He, Chenjie Wu, Yuanlai Xu, Jingjing Hu, Zhigao Xu e Ruan Chi. "Study on the Leaching Kinetics of Weathered Crust Elution-Deposited Rare Earth Ores by Hydroxypropyl Methyl Cellulose". Minerals 13, n. 9 (31 agosto 2023): 1156. http://dx.doi.org/10.3390/min13091156.
Testo completoAbstract (sommario):
In the process of the in situ leaching of weathered crust elution-deposited rare earth ores (WCE-DREOs), there are many problems in the conventional leaching agent, such as a slow leaching rate, low leaching yield and long leaching period. In order to solve the above problems, 2.0 wt% ammonium sulfate was mixed with hydroxypropyl methyl cellulose (HPMC). The effects of the HPMC concentration, temperature, pH and flow rate on the leaching kinetics of rare earth (RE) and aluminum (Al) were investigated. The results showed that when the concentration of HPMC was 0.05 wt%, the leaching equilibrium time of RE and Al was about 60% shorter than that of single ammonium sulfate. With an increase in the leaching temperature, the leaching equilibrium time of RE and Al decreased, and the apparent activation energy of RE and Al was 23.13 kJ/mol and 17.31 kJ/mol, respectively. The leaching process was in line with the internal diffusion kinetic control model. When the pH of the leaching agent was 4.02~8.01, the leaching yield of RE and Al was basically the same, but the leaching yield of Al was greatly increased at pH 2.0 due to a large amount of adsorbed hydroxy-Al in the RE ore eluded. The leaching yield reached the maximum when the flow rate was 0.7 mL/min. The leaching time and the leaching cost of RE can be saved by the composite leaching agent. The results provide theoretical guidance for the development and industrial application of the new composite leaching agent.
32
Wu, Xiaoyan, Jian Feng, Fang Zhou, Chufan Liu e Ruan Chi. "Optimization of a Rare Earth and Aluminum Leaching Process from Weathered Crust Elution-Deposited Rare Earth Ore with Surfactant CTAB". Minerals 14, n. 3 (20 marzo 2024): 321. http://dx.doi.org/10.3390/min14030321.
Testo completoAbstract (sommario):
Ammonium sulfate is typically employed as a leaching agent in the in situ leaching of weathered crust elution-deposited rare earth ore. However, it is associated with challenges such as low efficiency in mass transfer for rare earth (RE) leaching, high usage of the leaching agent, and prolonged leaching duration. To address the issues mentioned above, the surfactant cetyltrimethyl ammonium bromide (CTAB) was compounded with 2% ammonium sulfate to form a leaching agent in this paper. The effects of CTAB concentration, temperature, pH, and leaching agent flow rate on the rare earth (RE) and aluminum (Al) leaching mass transfer process from RE ore were investigated using chromatographic plate theory. The results revealed that CTAB addition improved the RE mass transfer process while moderately inhibiting the Al mass transfer efficiency. Increasing the temperature and pH of the leaching solution led to higher theoretical plate numbers for RE and Al leaching, lowered theoretical plate height (HETP), and enhanced leaching mass transfer efficiency. However, under high temperature and alkaline conditions, the mass transfer efficiency begins to decrease, indicating that high temperature and alkaline conditions are not conducive to the synergistic enhancement of RE and Al leaching by CTAB. Considering that clay minerals have good pH buffering properties, adjusting the pH of the leaching solution during rare earth ore leaching operations was deemed unnecessary. The optimal mass transfer conditions for leaching RE and Al were identified as 2% ammonium sulfate concentration, 0.00103 mol/L CTAB concentration, pH range of 5.2–5.5 for the leaching solution, 0.6 mL/min leaching solution flow rate, and room temperature. The rare earth leaching mass transfer effect could be enhanced during summer operations.
33
Liu, Song Li. "Experimental Study of Leaching Scandium from Chloride Dust". Advanced Materials Research 548 (luglio 2012): 305–8. http://dx.doi.org/10.4028/www.scientific.net/amr.548.305.
Testo completoAbstract (sommario):
Scandium is concentrated in the dust during TiO2 chlorization. The dust can be used as a raw material from which Scandium is extracted. Scandium leaching conditions such as leaching acid concentration , liquid-solid ratio , leaching temperature and leaching time is investigated with chemical analysis through the orthogonal experiment. The results show that the optimum leaching conditions is: chloride dust particle size is 44 μ m, leaching acid concentration is 15%, liquid-solid ratio is 2:1, leaching temperature is 28 °C, leaching time is 1 h.
34
Zhu, Chao, Bao Liang Ge, Zhao Yi Lu e Wen Zhu. "Biooxidation Pretreatment Cyanide Leaching of a Flotation Gold Concentrate". Advanced Materials Research 581-582 (ottobre 2012): 1106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.1106.
Testo completoAbstract (sommario):
This study reached a gold ore which contain 3.83g/t gold, to investigate the available gold recover methods, direct cyanide leaching test and “biooxidation-cyanide” leaching process were utilized after enrich gold by flotation. When regrinding the flotation concentrate to 95% -325mm, the leaching rate of “biooxidation-cyanide” leaching reached 94.47%, compare with direct leaching, the leaching rate increased almost 67%. Obviously bacterium oxidation is a useful pretreatment for gold leaching.
35
Zhang, Gui Fang, Peng Yan e Qing Rong Yang. "Experimental Study on Concentrating Scandium by Leaching from Associated Scandium Ore". Advanced Materials Research 734-737 (agosto 2013): 1033–36. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.1033.
Testo completoAbstract (sommario):
Based on the benefication of the complex silicate ore containing scandium, the research about aid-leaching agent used in the leaching of the scandium concentrate was been conducted. And the suitable leaching agent and aid-leaching agent which the useful ions entered into leaching liquid and the harmful ions were kept in leaching residue were been found according to the experiment results. For the scandium of sample existed various complex silicate ore as isomorphism form, the research has adopted hydrochloric acid with aid-leaching agent to dissociate the silicate ore and make scandium entering into solution. The research results has shown that the scandium leaching rate could reach 92.06% under the optimal conditions which the hydrochloric acid concentration is 22.8%, the dosage of aid leaching agent is 6%, liquid solid ratio is 4:1, particle size of leaching material totally is less than 0.15mm and leaching time is 8h.
36
Bucur, C., C. Ichim e I. Florea. "14C Release from TRIGA irradiated graphite". Radiocarbon 60, n. 6 (21 novembre 2018): 1819–29. http://dx.doi.org/10.1017/rdc.2018.131.
Testo completoAbstract (sommario):
ABSTRACTLeaching tests were carried out in aerobic and anaerobic conditions to assess the 14C released from TRIGA irradiated graphite. Both total 14C and inorganic and organic fractions in the leachant solutions were measured. The experimental results obtained from the leaching tests confirm the low 14C release rate in alkaline environment. Less than 2% of the total 14C inventory in the specimens subject to the leaching tests was released as dissolved species. Both inorganic and organic 14C species are released in alkaline conditions, with more inorganic 14C release under aerobic conditions (around 68% of the total 14C released was released as inorganic dissolved species), and more organic 14C species in anaerobic conditions (around 65% of the total 14C released was released as organic dissolved species). Both for anaerobic and aerobic conditions, the leaching rates are high in the first days of immersion and decrease after that, indicating a two stage process: an initial quick release (less than 9 × 10–02 % of inventory/day for the first 48 days) followed by a slower release rate (around 4 × 10–03 % of inventory/day).
37
He, Qiang, Jiang Qiu, Minglu Rao e Yanfei Xiao. "Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent". Minerals 11, n. 7 (2 luglio 2021): 716. http://dx.doi.org/10.3390/min11070716.
Testo completoAbstract (sommario):
During the leaching process of ionic rare earth ore (ICREO), ion-exchangeable phase calcium (IEP-Ca) and ion-exchangeable phase aluminum (IEP-Al) are leached along with rare earth, which causes many problems in the enrichment process, such as increasing the precipitant agent consumption and rare earth loss, etc. The agitation leaching kinetics and the column leaching mass transfer process of IEP-Ca and IEP-Al were studied to understand the leaching behavior of impurity in ICREO, which provides guides for the adjustment of the leaching process and to limit the co-leaching of impurities. IEP-Ca and IEP-Al were leached by ion exchange, with the leaching agent cations and the leaching kinetics described by an internal diffusion-controlled shrinking core model with an apparent activation energy of 8.97 kJ/mol and 10.48 kJ/mol, respectively. In addition, a significant reduction in the leaching efficiency of aluminum was caused by the hydrolysis reaction reinforced by the increase in MgSO4 concentration and temperature. The leaching kinetic data of IEP-Ca and IEP-Al was verified by the column leaching mass transfer process. There was a synchronous increase in the peak concentration of the outflow curve and leaching efficiency of calcium with the concentration of MgSO4 since IEP-Ca was easily leached. Therefore, as the leaching efficiency of calcium was already very high in the 0.20 mol/L MgSO4 leaching process, the leaching rate of calcium was limited by the leaching temperature and injection rate of MgSO4. For aluminum, the hydrolysis of Al3+ was promoted by increasing the MgSO4 concentration and the leaching temperature, thereby effectively reducing the content of aluminum in the leachate.
38
Chen, Kaihua, Jiannan Pei, Shaohua Yin, Shiwei Li, Jinhui Peng e Libo Zhang. "Leaching behaviour of rare earth elements from low-grade weathered crust elution-deposited rare earth ore using magnesium sulfate". Clay Minerals 53, n. 3 (settembre 2018): 505–14. http://dx.doi.org/10.1180/clm.2018.37.
Testo completoAbstract (sommario):
ABSTRACTThe present study investigates the use of magnesium sulfate (MgSO4) instead of (NH4)2SO4 as a lixiviant in the recovery of rare earth elements (REEs) from clays. Experiments were carried out to investigate the influence of leaching conditions such as leaching time, lixiviant concentration and liquid:solid ratio on the leaching efficiency. The optimum leaching conditions, leading to 75.48% of total REE leaching efficiency, required a stirring speed of 500 rpm, a leaching time of 30 min, a lixiviant concentration of 3 wt.% and a liquid:solid ratio of 3:1. After extension of the leaching process by a second stage, the leaching efficiency may reach up to 96.19%, which is slightly higher than that obtained by (NH4)2SO4. Leaching varies from element to element, with Ce presenting the lowest leaching efficiency, and the partition in leaching solution is in agreement with that in raw ore other than for Ce. Based on these findings, MgSO4 lixiviant is an excellent alternative leaching agent for a sustainable REE industry because it reduces or eliminates NH4+–N pollution.
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Chen, Yanbo, e Junjie Wang. "Experimental Study on the Dressing and Smelting of a Pyrrhotite-bearing Primary Gold Ore". E3S Web of Conferences 385 (2023): 03005. http://dx.doi.org/10.1051/e3sconf/202338503005.
Testo completoAbstract (sommario):
The content of pyrrhotite in a primary gold mine containing pyrrhotite is 0.68%. In the process of alkaline leaching pretreatment, there are problems such as large ore quantity and high alkali consumption. In the process of cyanide leaching, there are problems such as high cyanide consumption and slow gold leaching rate. In order to solve these problems, combined with production practice, experimental studies on magnetic separation, magnetic separation tailings leaching, magnetic separation concentrate alkali leaching pretreatment - leaching, magnetic separation concentrate flotation - cyanide leaching, etc. were carried out. A new process of "magnetic separation-magnetic flotation flotation flotation flotation flotation alkali leaching pretreatment mixed cyanide leaching" has been developed to reduce the pretreated minerals to less than 2% of the original ore, which is higher than the gold leaching rate of the conventional "alkali leaching pretreatment cyanide leaching" process, and the alkali (sodium hydroxide) consumption and cyanide (sodium cyanide) consumption are reduced by 80.83% and 32% respectively, and the annual reagent cost is saved by more than 600000 yuan.
40
Shibata, Junji, Shuji Gonomaru e Hideki Yamamoto. "Leaching Velocity of Precious Metals with Various Leaching Agents." KAGAKU KOGAKU RONBUNSHU 27, n. 3 (2001): 367–72. http://dx.doi.org/10.1252/kakoronbunshu.27.367.
Testo completo
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Zhang, Lei, Hao Wang e Yu Li. "Research on the Extract Al2O3 from Coal Gangue". Advanced Materials Research 524-527 (maggio 2012): 1947–50. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1947.
Testo completoAbstract (sommario):
The experiments selected Wang Taipu gangue as raw materials and adopted single factor experimental method to study the leaching of aluminum oxide from gangue by using hydrochloric acid as leaching medium. The experiments studied solvent/sample mass ratio, hydrochloric acid/sample, liquid-solid ratio, hydrochloric acid concentration, leaching time and leaching temperature on Al2O3 leaching rate of coal gangue. Through the parallel experiment of the above factors, we can found that optimization conditions of hydrochloric acid leaching of alumina were: solvent /sample mass ratio: 0.20, solvent: NaF, liquid-solid ratio: 1:10, hydrochloric acid concentration: 6mol/L, leaching time: 150min, leaching temperature:110°C. In this case, the aluminum oxide of optimal leaching rate was 79.33%.
42
Yang, Yong Qiang, Cheng Yan Wang, Dun Fang Li, Fei Yin, Yong Qiang Chen e Xiao Wu Jie. "Study on the Leaching of LiCoO2 in Low H2SO4 Concentration Solutions". Advanced Materials Research 201-203 (febbraio 2011): 1752–56. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.1752.
Testo completoAbstract (sommario):
The leaching behavior of battery grade lithium cobalt oxide (LiCoO2) was studied in Na2SO3-H2SO4 aqueous solutions with low H2SO4 concentration. The effects of H2SO4 concentration, leaching time, leaching temperature, and dosage of Na2SO3 on the leaching rate of LiCoO2 were investigated. The experimental results show that all the cobalt in LiCoO2 can be dissolved in the following conditions: the H2SO4 concentration of 0.4 mol/L, the leaching time of 0.5 h, the leaching temperature of 70°C and the Na2SO3 dosage being equal to the weight of LiCoO2. It is proved that the leaching of LiCoO2 in the system of Na2SO3-H2SO4 solutions is much more effective than that in other leaching systems. Moreover, the consumption of H2SO4 can be lowered greatly. Based on the leaching of pure LiCoO2, the Na2SO3-H2SO4 leaching system is further applied in the treatment of spent Li-ion battery and the leaching rate of cobalt can be achieved as higher as more than 98%.
43
Zhang, Ze Biao, Wan Kun Wang e Jin Hui Peng. "Innovative Process of Leaching of Nickel Supported Activated Carbon in Ammonium Sulfate". Advanced Materials Research 201-203 (febbraio 2011): 1774–79. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.1774.
Testo completoAbstract (sommario):
The leaching tests of nickel supported activated carbon under normal pressure in (NH4)2SO4were studied. The effects of experimental condition, such as initial concentration of (NH4)2SO4, liquid-to-solid ratio, leaching time and leaching temperature on the leaching rate of nickel, were investigated. The results show that the leaching rate of nickel is 96.12% with initial concentration of (NH4)2SO4of 7.5%, liquid-to-solid ratio of 2, leaching time of 5h and leaching temperature of 25°C. The morphology of nickel supported activated carbon before and after leaching was characterized by XRD, which proved the effective separation of nickel and activated carbon. The leaching rate of nickel was also shown better at room temperature and atmospheric pressure. Moreover, it needn’t equipments enduring high-pressure and high temperature in the leaching process, thus reducing the costs of leaching equipments greatly. This work provides a new way to the comprehensive utilization of nickel-containing activated carbon.
44
Cheng, An, Sao Jeng Chao, Wei Ting Lin e Jia Liang Chang. "Prediction of the Deterioration Depth of Concrete by Accelerating Calcium Leaching Test". Advanced Materials Research 365 (ottobre 2011): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amr.365.3.
Testo completoAbstract (sommario):
The concrete is a solid and porous composite materials, when the concrete exposure to moisture environment for a long-term, the pore water will penetrate into concrete cause hydration products leaching. Leaching of calcium ions increase in porosity and resulting in harmful ions ingress into concrete to reduce strength and durability of concrete. The purpose of this study is to evaluate the effect of water-binder ratio on calcium ion leaching behavior of cement-based material. The ammonium nitrate solution was used to accelerate leaching process. Leaching duration was 56 days, 91 days and 140 days, respectively. The leaching depth and compressive strength were measured. The results showed that leaching resistance increased with a decrease in water/binder ratio. The leaching depth showed that leaching behavior of the specimens without minerals admixtures can be divided into two stages, the first stage was leaching of calcium hydroxide and than the C-S-H gel were leaching.
45
Chen, Yuqian, Junwen Zhou, Libo Zhang, Jinhui Peng, Shiwei Li, Shaohua Yin, Kun Yang e Yaping Lin. "Microwave-assisted and regular leaching of germanium from the germanium-rich lignite ash". Green Processing and Synthesis 7, n. 6 (27 novembre 2018): 538–45. http://dx.doi.org/10.1515/gps-2017-0137.
Testo completoAbstract (sommario):
Abstract Demand for germanium (Ge) is rapidly growing in recent years in various fields including semiconductors, aerospace, and solar cells. However, the Ge resources are very limited in the world. Hence, in this work, microwave-assisted leaching and conventional leaching methods are employed for the leaching of Ge from the Ge-rich lignite ash (GA). The effects of leaching temperature, leaching time, initial acid concentration, oxidizing agent amount, and stirring speed on leaching of Ge were investigated and microwave-assisted and conventional methods of leaching were compared. Here, HCl solution is used as a leaching agent, and MnO2 is used as an oxidizing agent. From the results, the leaching rate of Ge was found to be 89.49% in the microwave-assisted method, and 83.62% in the conventional leaching method. The optimal conditions for microwave-assisted method include a leaching temperature of 65°C, a leaching time of 90 min, an oxidizing agent amount of 10 g/l, an initial acid concentration of 10 mol/l, and a stirring speed of 250 rpm. The leaching rate of Ge significantly improved in the microwave-assisted method as compared to the conventional method. Therefore, the microwave-assisted method is a suitable method for the leaching of Ge from the GA and is a novel way for the efficient utilization of Ge concentrate.
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Liu, Dan, Shu Ming Wen, Yong Jun Xian, Hai Ying Shen, Jiu Shuai Deng e Dan Dan Wu. "Recovery of Copper from Flotation Tailings by Leaching". Applied Mechanics and Materials 325-326 (giugno 2013): 128–32. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.128.
Testo completoAbstract (sommario):
A technology route of Reverse flotation of acid-consuming gangue mineralsAcid leaching for copperExtractingElectrodepositing is proposed for recovery copper from a tailings with high content of calcium oxide and magnesium oxide and high content of combined copper oxide. The effect of H2SO4concentration, leaching time and stirring speed on copper leaching was investigated. The leaching solution obtained under the optimal copper leaching conditions, was used to be proceeded for extracting and electrodepositing test. The best leaching conditions are stirring speed of 30 m/min, H2SO4concentration of 150 Kg/t ore, leaching time of 30 minutes. Under the best conditions, the acid leaching test presented that the production of per ton copper consumes sulfuric acid of 17.31 t, and Cu leaching rate is 84.70%.
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Han, Jiahong, Shujuan Dai, Jiushuai Deng, Shandong Que e Yugao Zhou. "Technology for Aiding the Cyanide Leaching of Gold Ores". Separations 11, n. 8 (26 luglio 2024): 228. http://dx.doi.org/10.3390/separations11080228.
Testo completoAbstract (sommario):
Cyanide leaching technology was studied for low-grade oxidized gold ores in Guangxi Province. The gold grade of the raw ores was 1.32 g/t. The gold leaching rate was 90.91% under the optimal conditions for the following conventional leaching process: using steel forging as the grinding medium, a grinding fineness of −0.074 mm accounting for 92.53%, a stirring speed of 1500 r/min, a pulp leaching concentration of 28.57%, a pH value of 10.5, a temperature of 25 °C, a leaching time of 24 h, and a potassium cyanide consumption of 4 kg/t. A new type of mixed aid-leaching agent (0.6 kg/t) was used, with a dosage of potassium cyanide of 2 kg/t. All else being equal, the gold leaching rate increased by 2.17% to 93.20% after 18 h of aid leaching compared to that of conventional leaching for 28 h. Meanwhile, the amount of potassium cyanide used was reduced by 50%. The aid-leaching agents restored the surface activity of passivated gold particles and depressed the adsorption of gold and its complexes by gangue minerals. This approach could shorten the leaching time and increase the gold leaching rate.
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He, Wei, Guo Hua Ye e Xiong Tong. "Study on Direct Acid Leaching Vanadium without Grinding and Roasting from Clay Vanadium Ore in Hunan". Applied Mechanics and Materials 316-317 (aprile 2013): 882–86. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.882.
Testo completoAbstract (sommario):
Abstract：A new technology of direct acid leaching vanadium without grinding and roasting was put forward, and the effects of leaching factors including dosage of sulfuric acid, type and dosage of assistant leaching agent, leaching time and temperature, liquid-solid ratio on the vanadium leaching rate were systematically investigated. The results show that vanadium leaching rate could be up to 92.58% under the optimal conditions of sulfuric acid dosage of 30%, MnO2 as assistant leaching agent and its dosage of 1.5%, leaching time of 6h, leaching temperature of 90°C, liquid-solid ratio of 1:1, and the leaching performance is perfect. Due to leaving out the high costing grinding system and the complex roasting system, the new technology has advantages in shortening the process, decreasing the cost, avoiding pollution generated by roasting comparing with the traditional technologies, and it can meet the requirement of modern metallurgy very well.
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Xu, Shuan, Yan Hai Shao e Ming Ming Li. "Extract Vanadium and Molybdenum from Spent Catalyst". Advanced Materials Research 926-930 (maggio 2014): 128–31. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.128.
Testo completoAbstract (sommario):
Based on the analysis of the properties of spent catalyst, extract vanadium and molybdenum from spent catalyst by roasting alkaline leaching. Sodium carbonate was leaching agent. The effects of roasting temperature, roasting time, the concentration of sodium carbonate and the number of leaching times on the leaching rate of vanadium and molybdenum were studied. Roasting temperature of 650°C, roasting time of 3h, the concentration of sodium carbonate of 50g/L and once counter-current leaching, under this condition, the leaching of vanadium is 83% and the leaching of molybdenum is 93%.Roasting alkaline leaching has good effect on extracting vanadium and molybdenum from spent catalyst.
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Jiang, Yan, Gan Xie, Rui Min Xiao, Du Shu Huang, Zi Jing Li e Li Da Sun. "Experimental Investigation of Indium Extraction by Sulfuric Acid Precure Pressure-Atmospheriation Leaching from Tin Dust". Advanced Materials Research 634-638 (gennaio 2013): 3211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.3211.
Testo completoAbstract (sommario):
Sulfuric Acid precure Pressure-atmospheriation leaching process from tin dust was studied. The factors had been investigated,which effects indium leaching rate,the factors are :the sulfuric acid initial temperature, curing time of heat, acid dosage, leaching reaction time, leaching temperature, the liquid-solid ratio and so on.The results show that the indium, zinc and tin leaching rate can be 96.68%, 97.70% and 0.52%,while pressure-atmospheriation leaching is carried out under the initial temperature 140°C,sulfuric acid, the time of heat aging 40 min, acid dosage and tin of tobacco smoke mass ratio0.7:1, leaching time 1.5h, leaching temperature 90°C,and the liquid-solid ratio 4:1 conditions.